Sammanfattning
Background. Pharmacogenetic testing is used to reveal genetic causes of variation in drug response. There is limited documentation of the usefulness of this kind of testing in ordinary clinical practice. The purpose of the study was to obtain a systematic overview of the outcome of CYP2D6 genotyping in a diagnostics laboratory.
Materials and method. We reviewed retrospectively all samples (n = 328) submitted to our laboratory with a request for CYP2D6 genotyping in the period 29 June 1998 - 28 December 2009 and classified them into three different indication groups on the basis of the information in the requisition. These samples and samples from a Control Group consisting of 100 healthy blood donors were scanned for the four most frequently occurring non-functional CYP2D6 alleles among Europeans and for duplications of the CYP2D6 gene associated with ultra-rapid drug metabolism.
Results. 325 patient samples were included. The percentage of ultrarapid metabolisers was statistically significantly higher in the patient group (4.0?%, p = 0.045) than in the Control Group (none), with the highest percentage of findings in the subgroup of patients who according to the requisition used a known CYP2D6 substrate. The percentage of poor metabolisers was not statistically significantly higher in the patient material (8.3?%) than in the Control Group (6.0?%) (p = 0.528).
Interpretation. The CYP2D6 analysis could only provide a limited explanation for side effects or therapeutic failure, despite the fact that the analysis was performed on a selected group of patients with clinical problems concerning their pharmacological treatment. This is probably due to lack of or a weak indication for genetic testing, and that the CYP2D6 genotype is only one of many factors that determine the individual response to a drug.